1. Field of the Invention
The present invention is related to a pixel array, and more particular to a pixel array having storage capacitors.
2. Description of Related Art
With the rapid development and application of information technology, wireless mobile communication, and informational household appliances, a good number of informational products are now using a touch panel as an input device instead of a conventional input device such as a keyboard or a mouse, wherein a touch-sensing display has become one of the most popular products on the current market.
Generally, the touch panel is a panel with an additional film layer having the touch sensing capability formed thereon. However, the manufacturing process of this kind of plug-in type touch panel has an additional step of assembling the panel and the touch sensing film layer, and the touch sensing film layer leads to the decreasing of the transmittance of the touch panel and the increasing of the thickness of the touch panel. Hence, the touch sensing film layer additionally assembled on the panel is disadvantageous for the progress of the panel towards to the lightness, slimness, shortness and compactness.
Accordingly, the conventional technique develops an in-cell type touch panel, in which the touch sensing film layer is integrated within the panel. Currently, the in-cell type touch panels are generally categorized into resistance type, capacitance type, optical type, acoustic wave type, and magnetic type. In the in-cell resistance type touch panel, a plurality of touch sensing conductors are formed on the opposite substrate and the photo spacer, and a plurality of touch sensing pads are formed on the active device array substrate. When the user presses the opposite substrate, the touch sensing conductors on the photo spacer conducts the touch sensing pads on the active device array substrate to locate the position pressed by the user.
FIG. 1A is a top view showing a color filter of a conventional in-cell type touch panel. FIG. 1B is a top view showing an active device array substrate accompanying with the color filter shown in FIG. 1A. As shown in FIG. 1A, in the conventional in-cell type touch panel, the red resins 112, the blue resin 114 and the green resins 116 for composing the color filter 110 are respectively arranged into stripes. In other words, the red resins 112 are arranged into several columns, the blue resins 114 are arranged into several columns, and the green resins 116 are arranged into several columns. Further, the resins with different colors are not arranged in the same column.
As shown in FIG. 1A together with FIG. 1B, in the conventional in-cell type touch panel, the active device array substrate D comprises a plurality of scan lines 120, a plurality of data lines 130, a plurality of pixels 140, a plurality of touch sensing units 150 and a plurality of common lines 160. The scan lines 120 intersect with the data lines 130 to define a plurality of sub-pixel regions S1 arranged in an array. Any three adjacent sub-pixel regions S1 together form a pixel region S. The pixels 140 are respectively located in the corresponding pixel regions S. Each of the pixels 140 has three sub-pixels 142, which are located in the three sub-pixel regions S1 of the pixel region S. In order to consist with the strip arrangement of the red resins 112, the blue resin 114 and the green resins 116 on the color filter 110, the sub-pixels 142 are arranged in strips.
More specifically, each of the sub-pixels 142 comprises an active device 142a, a pixel electrode 142b and a storage capacitor 142c. Each of the active devices 142a is connected between the corresponding pixel electrode 142b and the data line 130. The common lines 160 cross sub-pixel regions S1 in the same column and electrically connected to the storage capacitors 142c in the sub-pixel regions S1 in the same column. The common lines 160 are disposed under the peripheries of the pixel electrodes 142b and to overlap the pixel electrodes 142b. Moreover, each of the touch sensing units 150 is disposed in the corresponding pixel region S and crosses the three adjacent sub-pixel regions S1.
Each of the sub-pixel regions S1 has the storage capacitor 142c and each of the storage capacitors 142c has a capacitor upper electrode R1 and a capacitor bottom electrode R2. The capacitor upper electrode R1 is connected to the pixel electrode 142b and the capacitor bottom electrode R2 is connected to the common line 160. The capacitor bottom electrode R2 is disposed under the periphery of the pixel electrode 142b and to overlap the capacitor upper electrode R1. The capacitor bottom electrode R2 is an opaque metal layer. Since each of the sub-pixel regions S1 is configured with a storage capacitor 142c and the opaque capacitor bottom electrode R2 overlaps the periphery of the pixel electrode 142c, the aperture ratio of the pixel 140 is decreased.
Further, since it is necessary for the common lines 160 to connect the capacitor bottom electrode R2 of each of the storage capacitors 142c, the common lines 160 need to cross each of the sub-pixel regions S1. Hence, the common lines 160 shield each of the pixel electrodes 142b and the aperture ratio of the pixels 140 is decreased.
Moreover, in order to avoid the light leakage, it is necessary to form a black matrix on the pixel region S to shield the storage capacitors 142c and the common lines 160. Further, in order to ensure the shielding effect of the black matrix, the area of the black matrix should be larger than the total area of the storage capacitors 142c and the common lines 160. More specifically, in order to completely cover the common lines 160 and the storage capacitors 142c, the periphery of the pattern of the black matrix is arranged beyond the peripheries of the common lines 160 and the storage capacitors 142c. Hence, the larger the length of the peripheral regions of the common lines 160 or the capacitor bottom electrodes R2 of the storage capacitors 142c overlapping the pixel electrodes 142b is and the larger the area of the black matrix is, the smaller the aperture ratio of the pixel 140 is.
Since the conventional common lines 160 and the capacitor bottom electrodes R of the storage capacitors 142c are all disposed under the periphery of the pixel electrodes 142b, the peripheral regions of the common lines 160 or the capacitor bottom electrodes R2 of the storage capacitors 142c overlapping the pixel electrodes 142b is stripe type with an extremely large length. Thus, the area of the corresponding black matrix is relatively large and the black matrix over covers the pixel electrodes 142b. Hence, the aperture ratio is decreased.